Capacitor and method forming the same



June 7, 1932. J, BUTLER 1,862,297

CAPACITOR AND METHOD FORMING 'THE SAME Filed March 15. 1929 INVENTOR Bmmh 51466;

ATTORNEY Patented June 7, 1932 UNrrEn STATES PATENT ri-ica BENJAMIN J.BUTLER, OF SOMERVILLE, MASSACHUSETTS, ASSIGNOR, JBY MESNE AS- SIGNMENTS, T GENERAL ELECTRIC CGIMPANY, A CORPORATIUN OF NEW YORK CAPACITORAND HIETHOD FORMING- THE SAME Application filed March 15, 1929. fierialNo. 347,271.

This invention relates to capacitors which include an improved anchorfor the terminal tabs such as are used in paper condensers.

Hitherto in the manufacture of rolled paper or series stack condenserscomprising alternate sheets of dielectric and foil wound on a mandrel,or assembled in alternate layers, it has been customary to insert stripsof foil in contact with the armatures of opposite polarity to serve asterminals for such armatures. In the manufacture of paper condensers ofsmall capacity, the thinness of the roll, i. e., the small number ofturns of paper and foil does notgive suflicient pressure to grip theterminal tabs, the result being that the tabs are often disarranged orpulled out of position in the subsequent handling and processing of theunit. An attempt to overcome this diflicultv has been made by providingterminal tabs with a plurality of anchoring lugs or extensions. Thesemembers are difficult and costly to make, involving expensive tools topunch out the variegated shapes of terminals, and in addition, the extrametal required for these difi'erent shapes increases the cost verymarkedly.

It is an object of the present invention to provide an improved terminaltab for paper condensers, which is characterized by its simplicity ofstructure and ease of manufacture and insertion.

It is a further object of this invention to provide such a terminal tabwhich is economical to manufacture and permits marked economies in thepreparation of the finished condenser.

In the drawing, like numerals refer to similar parts of the severalviews, of which Fig. 1 'is a plan view of an improved tab terminal ofthe present invention;

Fig. 2 is a perspective view of a paper condenser showing in dottedlines the location of the tabs when in use; and

Fig. 3 is a section taken on line 33 of Fig. 2 showing the locking ofthe tab by the condenser foils and dielectrics.

As noted, the terminal tab, designated gencrally by the numeral 1,comprises a generally rectangular strip of metal, the preferredembodiment being tinned brass, although it will be understood that anysuitable metal, such as tin foil or the like, may be used. This terminalstrip may be made of stock .002 of an inch thick and A of an inch wide,al-

though it will, of course, be fully appreciated that these dimensionsare given merely by way of example, and any variation in the size toaccommodate the structure to condensers of different capacities, isfully comprehended in the spirit and scope of this invention.

At one end of the terminal, one or more holes 2 of any suitable size andconfiguration are punched out of the metal. When such a terminal isinserted in a condenser roll between a sheet of flexible dielectric suchas paper and an armature, the paper and/or foil can be forced to enterinto the holes in the tab thus gripping the tab firmly, and preventingit from being pulled out.

Where capacitors of large dimensions are used, and terminal tab stripsof thicker or harder material inserted, the locking aperture or surfacebreak 2 may have its edge or edges suitably beveled, in order to preventrupture (by shearing) of the juxtaposed foils and dielectrics of thecapacitor by the edges of the terminal tab surface breaks or holes.

The tabs are shown in position in the rolled condenser of Fig. 2, thefoils being designate generally by the numeral 3 and the paperdielectric by the numeral 4. The foils are shown in dotted lines, theupper and lower boundaries being designated generally by the numerals 5and 6 respectively. The tabs are inserted in the condenser for asubstantial portion of their length, usually one-halt or more of theirtotal overall length, that is, the tabs extend into the capacitor overapproximately the total width of the capacitor 90 foil strips 3, theminimum distance being indicated in Fig.1 by the distance between dottedline 7 and the left end of tab 1. Butas shown in ll ig'. 2 a part ofthat length of tab 1 lies outside capacitor toils 3 and betweendielectric sheets i, so that when, as pre- "ferred, and as shown in Fig.3, a plurality; of holes 2 or depressions are formed in a row along thelength oftab 1, said row extends substantially over the entire length ofthe to!) terminal tab 1 which lies adjacent capacitor foils 3; theuseful result being that not only are the tabs 1 heldagainst foilstending to pull them out of the capacitor but are prevented from beingshifted into different angular positions inside the capacitor.

In the assembly of the condenser, the condenser elements are wound loosewith the terminal tabs inserted at the proper places in the roll. Thewound roll is then sent to the clamping room where it is pressed in aclamp by applying a pressure of substantially 25 to 50 pounds per squareinch. During this process of applying pressure, the dielectric sheetsand the foils enter the holes in the terminal tab, as can be appreciatedfrom an inspection of Fig. 3, thereby firmly anchoring the tab in itsposition in the roll. The tabs so anchored are so firmly held inposition that they cannot be pulled out without disrupting the condenserstructure proper, or being themselves torn, if made of soft metal. Aftercompression, the compressed unit is subjected to the usual impregnatingand finishing steps and then provided with suitable terminal leads, thewhole structure subsequently being inserted in a casing or canister andembedded in pot head or other insulating composition, if desired. Theimpregnating material, for cooling and solidifying aids in holding ininterlocking relations, the portions ofthe capacitor sheets which havebeen forced into the holes or depressions 2, even after the clamps havebeen removed.

It will be appreciated that the basic concept of this inventioncomprehends the idea of forcing the condenser body itself, i. e., thefoils and dielectrics into a depression in the tab so as to provide acombination of a frictional and a positive lock.

Since the total positive locking effect is a function of the contactingsurface of the depressed portions of the dielectric or foil or (asshown) both the dielectric and foil, it will be appreciated that theshape of the depressions in the tabs may be varied to suit theexigencies of any particular construction.

While the improved condenser is shown as comprising a tab having anaperture or hole, it will readily be appreciated that the advantages ofthe invention may be secured, in part, by forming the tab with a dishedportion or portions constituting a break on one or both sides of theflat surface of the tab in the same general sense in which the holeconstitutes such breaks inboth surfaces of the strip tab. Likewise itwill be understood that although a roll condenser has been described asa preferred embodiment the principles herein set forth are applicable topaper stack condensers.

The simplicity of the tab of the present invention permits a'markedsaving in manufacturing cost, due to the fact that a mere punchingoperation is required to provide a firm anchor, and the percentage ofrejections of finished condensers due to disarranged or torn terminalsis reduced to a minimum.

I claim: I j

1. A method of forming a capacitor, which consists in laying a terminaltab having flat surface broken in one part,between a continuous foil anda continuous dielectric to form part of a capacitor, and subjecting thecapacitor to sufficient pressure to cause the said foil anddielectric tobe displaced into close engagement with the interior of the break in thesurface, and impregnating the displaced parts to hold them in positionto lock the tab.

2. A'capacitor including a flat tab terminal having-a break in its fiatsurface, and continuous flexible foil and continuous flexible dielectricextending over the flat surface of the terminal and bending into and outof the break, said bends holding the tab against sliding on the foil anddielectric.

3. A capacitor including a. flat tab terminal having a hole in its flatsurface, and continuous flexible foil and continuous paper dielectricextending over the flat surface of the terminal and bending into and outof the hole to hold the tab against sliding on the foil and paper.

4. A capacitor including a flat tab terminal having a hole in its flatsurface, and layers of foil wound between a continuous sheet of paper,one of said layers extending across and lying in contact with said taband bend ing into and out of the hole to hold the tab against sliding onthe foil and paper.

5. A capacitor including a pair of flat tab terminals each having a holein its flat surface, a pair of continuous layers of foil, a

- sheet of continuous paper between said layers of foil, one of saidlayers extending across and lying in contact with one tab and bendinginto and out of the hole therein to hold the tab against sliding on thefoil and paper,

the other of said layers extending across and lying in contact with theother tab and bending into and out of thehole therein to hold the tabagainst sliding on the foil and paper.

6. A capacitor including a flat tab terminal having a hole in its flatsurface, a continuous flexible foil and continuous paper dielectricextending over the flat surface of the terminal and bending into and outof the hole to hold the tab against sliding on the foil and paper, and acasing holding the foil and paper down on the tab.

7. In the art of making capacitors including adjacent sheets ofdielectric paper and of metal armature foil, the method of anchoringterminal strips in the interior of such a capacitor, which consists inwinding such sheets in a relatively loose roll. and placing a portion ofa terminal strip of which a relatively small portion is perforated. insuch position inside such capacitor that the perforated portion liesbetween and adjacent the paper and foil capacitor sheets"; thencompressing the loosely wound sheets and interposed terminal striptogether under substantial mechanical pressure thereby establishing goodelectrical. contact'between the surface of the foil-sheet armature andthe relatively large non-perforated surface of the terminal strip, andby said compression also forcing into the perforation in the terminalstrip, the portions of the sheets of paper and foil lying on oppositefaces of the terminal. strip adjacent the perforation thereby holdingthe portion of the terminal strip inside the capacitor in its positionadjacent the armature foil; and then impregnating the capacitorincluding the interior of the paper sheet thereby tending to maintainsaid mechanical and electrical relations of the paper dielectric andarmature foil respectively with the perforated andnon-perforatedportions of the terminal strip inside the capacitor.

8. In the art of making capacitors including adjacent sheets ofdielectric paper and L of metal armature foil, the method of anchoringterminal strips in the interior of such a capacitor, which consists inwinding said' sheets in a relatively loose roll and placing a. terminalstrip of which a relatively small portion is formed with a perforation,in such position inside such, capacitor that the perforated portion liesbetween and adjacent the paper and foil 35 capacitor sheets; and thencompressing the loosely wound sheets and interposed terminal striptogether under substantial mechanical pressure thereby establishin goodelectrical contact between the sur ace of the armature foil and therelatively large nonperforated surface of the terminal strip, and bysaid compression also forcing into the perforation in the terminalstrip, portions of the sheets of paper and foil lying on opposite facesof the terminal strip and adjacent the perforation thereof, therebyholding the portion of the terminal strip inside the capacitor in itsposition adjacent the armature foil.

9. In the art of making capacitors containingadjacent sheets ofdielectric paper and metal armature foil, the method of anchoringterminal strips in the interior of such a capacitor, which consists inwinding such sheets in a relatively loose roll and placing a portion ofa terminal strip of which a relatively small portion is formed with abreak in its surface, in such position inside such capacitor that thesurface-broken'porlion lies between and adjacent the paper and foilsheets; and then compressing the loosely wound sheets and interposedterminal strip together under substantial mechanical pressure therebyestablishing good electrical contact between the surface of thearmaturefoil and the relatively large non-broken surface of the terminalstrip, and by said compression also forcing into the break in theterminal strip, the portion of the surface of the capacitor sheet whichfaces the surfacebreak in the terminal strip and thereby holding theportion of the terminal strip inside the capacitor ,in its positionadjacent the armature-foil.

10. In the art of making capacitors including adjacent dielectric andconducting armature sheets, of which at least one is yieldable, themethod of anchoring a terminal strip in the interior of such acapacitor, which consists in placing a portion of a terminal strip whichis formed with a break in its surface, in such position inside suchcapacitor that its surface break lies adjacent said yieldable capacitorsheet; and then compressing the capacitor sheets and interposed terminalstrip together under substantial mechanical pressure therebyestablishing good electrical contact between the surface of the armaturesheet and the terminal strip, and by said compression also forcing intothe break of the terminal-strip, the portion of the yielding capacitorsheet which lies adj acent the surface-break of the terminal strip,thereby holding the portion of the terminal strip inside the capacitorin its positon adjacent the armature sheet.

11. In the art of making capacitors including adjacent dielectric andconducting armature sheets of which at least one is yieldable, themethod of anchoring a terminal strip in the interior of such acapacitor, which consists in placing a portion of a terminal strip whichis formed with a plurality of surface breaks located in succession inthe direction of its length, in such position inside such capacitorbetween the dielectric and armature sheets, that the broken surfaceportions of the terminal strip lie adjacent at least one yieldable sheetof the capacitor; and then compressing the capacitor and insertedterminal strip together under substantial mechanical pressure therebyestablishing good electrical contact between the armature sheet and theterminal strip, and by said compression also forcing the yieldablecapacitor sheet into the succession of surface breaks in the terminalstrip, holding the terminal strip in ing good electrical contact betweenthe armai ture surface and the non-broken surface of the terminal strip,and by such compression also forcing into the surface-break in theterminal strip, the portion of the aper sheet 5 lying adjacentsaid-break, there y holding the terminal strip in place adjacent thearmatime sheet against forces tending .to pull the terminal strip out ofplace adjacent the armature sheet.

13. In the art of making capacitors including a metal foil armature, themethod of anchoring a terminal strip in the interior of such acapacitor, which consists in placing a portion of a terminal stripformed with a surface break, in such position between the armature foiland-adjacent dielectric sheet that the surface break in the terminalstrip lies adjacent the armature foil; and compressing the capacitor andinserted terminal strip together under substantial mechanical pressureestablishing good contact between the surface of the armaturefoil andthe nonbroken portion of the surface of the terminal strip, and by suchcompression also forcing into the surface break in the terminal strip,that portion of the armature foil which lies adjacent said break,thereby holding the terminal strip in place against forces tending topull it out of place adjacent the armature foil.

In testimony whereof I hereunto aflix my signature.

' BENJAMIN J. BUTLER.

